Open Access. Powered by Scholars. Published by Universities.®

Computer Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Computer Sciences

1997

Institution
Keyword
Publication
Publication Type
File Type

Articles 1 - 30 of 50

Full-Text Articles in Computer Engineering

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole Dec 1997

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (Streaming Control Protocol) , for real-time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real-time streaming. First, it uses a congestion control policy ...


Modeling And Comparison Of Wormhole Routed Mesh And Torus Networks, Ronald I. Greenberg, Lee Guan Oct 1997

Modeling And Comparison Of Wormhole Routed Mesh And Torus Networks, Ronald I. Greenberg, Lee Guan

Computer Science: Faculty Publications and Other Works

2D-mesh and torus networks have often been proposed as the interconnection pattern for parallel computers. In addition, wormhole routing has increasingly been advocated as a method of reducing latency. Most analysis of wormhole routed networks, however, has focused on the torus and the broader class of k-ary n-cubes to which it belongs. This paper presents a performance model for the wormhole routed mesh, and it compares the performance of the mesh and torus based on theoretical and empirical analyses.


An Improved Analytical Model For Wormhole Routed Networks With Application To Butterfly Fat-Trees, Ronald I. Greenberg, Lee Guan Aug 1997

An Improved Analytical Model For Wormhole Routed Networks With Application To Butterfly Fat-Trees, Ronald I. Greenberg, Lee Guan

Computer Science: Faculty Publications and Other Works

A performance model for wormhole routed interconnection networks is presented and applied to the butterfly fat-tree network. Experimental results agree very closely over a wide range of load rate. Novel aspects of the model, leading to accurate and simple performance predictions, include (1) use of multiple-server queues, and (2) a general method of correcting queuing results based on Poisson arrivals to apply to wormhole routing. These ideas can also be applied to other networks.


Dynamic Load Distribution In Mist, K. Al-Saqabi, R. M. Prouty, Dylan Mcnamee, Steve Otto, Jonathan Walpole Jul 1997

Dynamic Load Distribution In Mist, K. Al-Saqabi, R. M. Prouty, Dylan Mcnamee, Steve Otto, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This paper presents an algorithm for scheduling parallel applications in large-scale, multiuser, heterogeneous distributed systems. The approach is primarily targeted at systems that harvest idle cycles in general-purpose workstation networks, but is also applicable to clustered computer systems and massively parallel processors. The algorithm handles unequal processor capacities, multiple architecture types and dynamic variations in the number of processes and available processors. Scheduling decisions are driven by the desire to minimize turnaround time while maintaining fairness among competing applications. For efficiency, the virtual processors (VPs) of each application are gang scheduled on some subset of the available physical processors.


A Toolkit For Specializing Production Operating System Code, Crispin Cowan, Dylan Mcnamee, Andrew P. Black, Calton Pu, Jonathan Walpole, Charles Krasic, Perry Wagle, Qian Zhang Jun 1997

A Toolkit For Specializing Production Operating System Code, Crispin Cowan, Dylan Mcnamee, Andrew P. Black, Calton Pu, Jonathan Walpole, Charles Krasic, Perry Wagle, Qian Zhang

Computer Science Faculty Publications and Presentations

Specialization has been recognized as a powerful technique for optimizing operating systems. However, specialization has not been broadly applied beyond the research community because the current techniques, based on manual specialization, are time-consuming and error-prone. This paper describes a specialization toolkit that should help broaden the applicability of specializing operating systems by assisting in the automatic generation of specialized code, and {\em guarding} the specialized code to ensure the specialized system continues to be correct. We demonstrate the effectiveness of the toolkit by describing experiences we have had applying it in real, production environments. We report on our experiences with ...


Predictable File Access Latency For Multimedia, Dan Revel, Crispin Cowan, Dylan Mcnamee, Calton Pu, Jonathan Walpole May 1997

Predictable File Access Latency For Multimedia, Dan Revel, Crispin Cowan, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Multimedia applications are sensitive to I/O latency and jitter when accessing data in secondary storage. Transparent adaptive prefetching (TAP) uses software feedback to provide multimedia applications with file system quality of service (QoS) guarantees. We are investigating how QoS requirements can be communicated and how they can be met by adaptive resource management. A preliminary test of adaptive prefetching is presented.


Provisioning On-Line Games: A Traffic Analysis Of A Busy Counter-Strike Server, Francis Chang, Wu-Chang Feng, Wu-Chi Feng, Jonathan Walpole May 1997

Provisioning On-Line Games: A Traffic Analysis Of A Busy Counter-Strike Server, Francis Chang, Wu-Chang Feng, Wu-Chi Feng, Jonathan Walpole

Computer Science Faculty Publications and Presentations

A poster that illustrates the client/server model employed by an multiplayer online game, focusing on bandwidth usage.


Mlpq: A Linear Constraint Database System With Aggregate Operators, Yiming Li Apr 1997

Mlpq: A Linear Constraint Database System With Aggregate Operators, Yiming Li

Computer Science and Engineering: Theses, Dissertations, and Student Research

In this project report, I will discuss a Multiple Linear Programming Query (MLPQ) system and the theoretical background of this system.The MPLQ system is developed to solve some realistic problems involving both linear programming (UP) techniques and linear constraint databases (LCDBs) theory. The MLPQ system is aimed at providing a mechanism of bridging these two important areas. system basically consists of three parts which are a linear constraint database, an LP solver, and an interface between the LCDB and the LP solver. The LCDB of the MLPQ system contains multiple linear programming problems. The LP solver used in the ...


A Global Computing Environment For Networked Resources, Haluk Topcuoglu, Salim Hariri Jan 1997

A Global Computing Environment For Networked Resources, Haluk Topcuoglu, Salim Hariri

Electrical Engineering and Computer Science

Current advances in high-speed networks and WWW technologies have made network computing a cost-effective, high-performance computing alternative. New software tools are being developed to utilize efficiently the network computing environment. Our project, called Virtual Distributed Computing Environment (VDCE), is a high-performance computing environment that allows users to write and evaluate networked applications for different hardware and software configurations using a web interface. In this paper we present the software architecture of VDCE by emphasizing application development and specification, scheduling, and execution/runtime aspects.


Lyceum: A Multi-Protocol Digital Library Gateway, Ming-Hokng Maa, Michael L. Nelson, Sandra L. Esler Jan 1997

Lyceum: A Multi-Protocol Digital Library Gateway, Ming-Hokng Maa, Michael L. Nelson, Sandra L. Esler

Computer Science Faculty Publications

Lyceum is a prototype scalable query gateway that provides a logically central interface to multi-protocol and physically distributed, digital libraries of scientific and technical information. Lyceum processes queries to multiple syntactically distinct search engines used by various distributed information servers from a single logically central interface without modification of the remote search engines. A working prototype (http://www.larc.nasa.gov/lyceum/) demonstrates the capabilities, potentials, and advantages of this type of meta-search engine by providing access to over 50 servers covering over 20 disciplines.


Physical Media Independence: System Support For Dynamically Available Network Interfaces, Jon Inouye, Jim Binkley, Jonathan Walpole Jan 1997

Physical Media Independence: System Support For Dynamically Available Network Interfaces, Jon Inouye, Jim Binkley, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Advances in hardware technology has fueled the proliferation of dynamically configurable network interface cards. This empowers mobile laptop users to select the most appropriate interface for their current environment. Unfortunately, the majority of system software remains "customized" for a particular network configuration, and assumes many network characteristics remain invariant over the runtime of the software. Physical Media Independence (PMI) is the concept of making assumptions about a particular device explicit, detecting events which invalidate these assumptions, and recovering once events are detected. This paper presents a model supporting PMI. Based on device availablilty, the model identifies implicit device-related assumptions made ...


Reasoning About Code Mobility With Mobile Unity, Gian Pietro Picco, Gruia-Catalin Roman, Peter J. Mccann Jan 1997

Reasoning About Code Mobility With Mobile Unity, Gian Pietro Picco, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Advancements in network technology have led to the emergence of new computing paradigms that challenge established programming practices by employing weak forms of consistency and dynamic forms of binding. Code mobility, for instance, allows for invocation-time binding between a code fragment and the location where it executes. Similarly, mobile computing allows hosts (and the software they execute) to alter their physical location. Despite apparent similarities, the two paradigms are distinct in their treatment of location and movement. This paper seeks to uncover a common foundation for the two paradigms by exploring the manner in which stereotypical forms of code mobility ...


An Introduction To Mobile Unity, Gruia-Catalin Roman, Peter J. Mccann Jan 1997

An Introduction To Mobile Unity, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Traditionally, a distributed system has been viewed as a collection of fixed computational elements connected by a static network. Prompted by recent advances in wireless communications rechnology, the emerging field of mobile computing is challenging these assumptions by providing mobile hosts with connectivity that may change over time, raising the possibility that hosts may be called upon to operate while only weakly connected to or while completely disconnected from other hosts. We define a concurrent mobile system as one where independently executing coponents may migrate through some space during the course of the computation, and where the pattern of connectivity ...


Compositional Programming Abstractions For Mobile Computing, Peter J. Mccann, Gruia-Catalin Roman Jan 1997

Compositional Programming Abstractions For Mobile Computing, Peter J. Mccann, Gruia-Catalin Roman

All Computer Science and Engineering Research

Recent advances in wireless networking technology and the increasing demand for ubiquitous, mobile connectivity demonstrate the importance of providing reliable systems for managing reconfiguration and disconnection of components. Design of such systems requires tools and techniques appropriate to the task. Many formal models of computation, including UNITY, are not adequate for expressing reconfiguration and disconnection and are therefore inappropriate vehicles for investigating the impact of mobility on the construction of modular and composable systems. Algebraic formalisms such as the pi-calculus have been proposed for modeling mobility. This paper addresses the question of whether UNITY, a state-based formalism with a foundation ...


End-User Visualization And Manipulation Of Distributed Aggregate Data, T. Paul Mccartney, Kenneth J. Goldman Jan 1997

End-User Visualization And Manipulation Of Distributed Aggregate Data, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

Aggregate visualization and manipulation enables the viewing and interaction of dynamically changing data sets in a graphically meaningful way. However, off-the-shelf applications typically provide only limited ways to view static aggregates and generally to not support manipulation of aggregate data through the resulting visualization. To be fully dynamic, an aggregate visualization should be customizable to suit the individual's needs and should allow end-users to modify the data through direct manipulation. This paper describes a software system that empowers end-users to create interactive aggregate visualizations through a visual language interface. Included are mechanisms for specifying how aggregate data is processed ...


Terabit Burst Switching, Jonathan S. Turner Jan 1997

Terabit Burst Switching, Jonathan S. Turner

All Computer Science and Engineering Research

This report summarizes the results of an architectural study on Terabit Burst Switching. The purpose of this study was to explore alternative architectures for very high performance switching for data communication, using a combination of optical and electronic technologies. We explore two alternative implementations of the burst switching concept in detail, one using a hybrid architecture with an electronic core, and an integrated architecture using an all optical data path. We also briefly discuss an approach using optical TDM. Our results show that using the hybrid architecture, it is feasible to construct systems with aggregate capacities of tens of terabits ...


Mobile Unity: A Language And Logic For Concurrent Mobile Systems, Peter J. Mccann, Gruia-Catalin Roman Jan 1997

Mobile Unity: A Language And Logic For Concurrent Mobile Systems, Peter J. Mccann, Gruia-Catalin Roman

All Computer Science and Engineering Research

Traditionally, a distributed system has been viewed as a collection of fixed computational elements connected by a static network. Prompted by recent advances in wireless communications rechnology, the emerging field of mobile computing is challenging these assumptions by providing mobile hosts with connectivity that may change over time, raising the possibility that hosts may be called upon to operate while only weakly connected to or while completely disconnected from other hosts. We define a concurrent mobile system as one where independently executing coponents may migrate through some space during the course of the computation, and where the pattern of connectivity ...


Optimizing The Performance Of The Corba Internet Inter-Orb Protocol Over Atm, Aniruddha Gokhale, Douglas C. Schmidt Jan 1997

Optimizing The Performance Of The Corba Internet Inter-Orb Protocol Over Atm, Aniruddha Gokhale, Douglas C. Schmidt

All Computer Science and Engineering Research

The Internet Inter-ORB Protocol (IIOP) enables heterogeneous CORBA-compliant Object Request Brokers (ORBs) to interoperate over TCP/IP networks. The IIOP uses the Common Data Representation (CDR) transfer syntax to map CORBA Interface Definition Langauge (IDL) data types into a bi-canonical wire format. Due to the excessive marshaling/demarshaling overhead, data copying, and high-levels of function call overhead, conventional implementation of IIOP protocols yield poor performance over high-speed networks. To meet the demands of emerging distributed multimedia applications, CORBA-compliant ORBs must support both interoperable and highly efficient IIOP implementations. This paper provides two contributions to the study and design of high ...


Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, Joe Hoffert, T. Paul Mccartney, Jerome Plun, Todd Rogers Jan 1997

Building Interactive Distributed Applications In C++ With The Programmers' Playground, Kenneth J. Goldman, Joe Hoffert, T. Paul Mccartney, Jerome Plun, Todd Rogers

All Computer Science and Engineering Research

The objective of The Programmers' Playground, described in this manual, is to provide a development environment and underlying support for end-user construction of distributed multimedia applications from reusable self-describing software components. Playground provides a set of software tools and a methodology for simplifying the design and construction of applications that interact with each other and with people in a distributed computer system. This manual explains how to write interactive distributed applications using Playground. The only background necessary to get started is an understanding of basic data structures and control constructs in C++. If you already know C++, then with the ...


Exact Learning Of Discretized Geometric Concepts, Nader H. Bshouty, Paul W. Goldberg, Sally A. Goldman, H. David Mathias Jan 1997

Exact Learning Of Discretized Geometric Concepts, Nader H. Bshouty, Paul W. Goldberg, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We first present an algorithm that uses membership and equivalence queries to exactly identify a discretized geometric concept defined by the unioin of m axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. This algorithm receives at most md counterexamples and uses time and membership queries polynomial in m and log(n) for any constant d. Furthermore, all equivalence queries can be formulated as the union of O(mdlog(m)) axis-parallel boxes. Next, we show how to extend our algorithm to efficiently learn, from only equivalence queries, any discretized geometric concept generated from any ...


Learning With Unreliable Boundary Queries, Avrim Blum, Prasad Chalasani, Sally A. Goldman, Donna K. Slonim Jan 1997

Learning With Unreliable Boundary Queries, Avrim Blum, Prasad Chalasani, Sally A. Goldman, Donna K. Slonim

All Computer Science and Engineering Research

We introduce a model for learning from examples and membership queries in situations where the boundary between positive and negative examples is somewhat ill-defined. In our model, queries near the boundary of a target concept may receive incorrect or "don't care" responses, and the distribution of examples has zero probability mass on the boundary region. The motivation behind our model is that in many cases the boundary between positive and negative examples is complicated or "fuzzy." However, one may still hope to learn successfully, because the typical examples that one sees to not come from that region. We present ...


Noise-Tolerant Distribution-Free Learning Of General Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias, Subhash Suri, Hisao Tamaki Jan 1997

Noise-Tolerant Distribution-Free Learning Of General Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias, Subhash Suri, Hisao Tamaki

All Computer Science and Engineering Research

We present an efficient algorithm for PAC-learning a very general class of geometric concepts over Rd for fixed d. More specifically, let T be any set of s halfspaces. Let x = (x1,...,xd) be an arbitrary point in Rd. With each t Є T we associate a boolean indicator function It(x) which is 1 if and only if x is in the halfspace t. The concept class Cds that we study consists of all concepts formed by any boolean function over It1, ...Its for ti Є T. This class is much more general than any geometric concept class known ...


A Theoretical And Empirical Study Of A Noise-Tolerant Algorithm To Learn Geometric Patterns, Sally A. Goldman, Stephen D. Scott Jan 1997

A Theoretical And Empirical Study Of A Noise-Tolerant Algorithm To Learn Geometric Patterns, Sally A. Goldman, Stephen D. Scott

All Computer Science and Engineering Research

Developing the ability to recognize a landmark from a visual image of a robot's current location is a fundamental problem in robotics. We describe a way in which the landmark matching problem can be mapped to that of learning a one-dimensional geometric pattern. The first contribution of our work is an efficient noise-tolerant algorithm (designed using the statistical query model) to PAC-learn the class of one-dimensional geometric patterns. The second contribution of our work is an empirical study of our algorithm that provides at least some evidence that statistical query algorithms may be valuable for use in practice for ...


An Algorithm For Message Delivery In A Micromobility Environment, Amy L. Murphy, Gruia-Catalin Roman, George Varghese Jan 1997

An Algorithm For Message Delivery In A Micromobility Environment, Amy L. Murphy, Gruia-Catalin Roman, George Varghese

All Computer Science and Engineering Research

With recent advances in wireless communication and the ubiquity of laptops, mobile computing has become an important research area. An essential problem in mobile computing is the delivery of a message from a source to either a single mobile node, unicast, or to a group of mobile nodes, multicast. Standard solutions proposed for macromobility (Mobile IP) and micromobility (cellular phones) for the unicast problem rely on tracking the mobile node. Tracking solutions scale badly when mobile nodes move frequently, and do not generalize well to multicast delivery. Our paper proposes a new message delivery algorithm for micromobility based on a ...


The Programmers' Playground Application Management System User Guide, William M. Shapiro, T. Paul Mccartney, E.F. Berkley Shands Jan 1997

The Programmers' Playground Application Management System User Guide, William M. Shapiro, T. Paul Mccartney, E.F. Berkley Shands

All Computer Science and Engineering Research

Application Management permits the advertising, launching, and configuring of distributed applications created using the Programmers' Playground. Applications can be documented and made available to end-users through the use of application pages on the World Wide Web. The launching and configuring of applications is performed by a brokerage system consisting of an applicatoin broker and one or more hierarchies of module launchers. This document describes how to setup and use the components of the Application Management system.


Replication Of The First Controlled Experiment On The Usefulness Of Design Patterns: Detailed Description And Evaluation, Lutz Prechelt, Barbara Unger, Douglas Schmidt Jan 1997

Replication Of The First Controlled Experiment On The Usefulness Of Design Patterns: Detailed Description And Evaluation, Lutz Prechelt, Barbara Unger, Douglas Schmidt

All Computer Science and Engineering Research

Advocates of software design patterns claim that using design patterns improves communication between software developers. The controled experiment that we describe in this report tests the hypothesis that software maintainers of well-structured, well-documented software containing design patterns can make changes (1) faster and (2) with less errors if the use of patterns is explicitly documented in the software. The experiment was performed with 22 participants of a university course on C++ and design patterns; it is similar to a previous experiment performed in Karlsruhe. For one of the two experiment tasks the experiment finds that both hypotheses appear to be ...


Sequence Assembly Validation By Restriction Digest Fingerprint Comparison, Eric C. Rouchka, David J. States Jan 1997

Sequence Assembly Validation By Restriction Digest Fingerprint Comparison, Eric C. Rouchka, David J. States

All Computer Science and Engineering Research

DNA sequence analysis depends on the accurate assembly of fragment reads for the determination of a consensus sequence. Genomic sequences frequently contain repeat elements that may confound the fragment assembly process, and errors in fragment assembly, and errors in fragment assembly may seriously impact the biological interpretation of the sequence data. Validating the fidelity of sequence assembly by experimental means is desirable. This report examines the use of restriction digest analysis as a method for testing the fidelity of sequence assembly. Restriction digest fingerprint matching is an established technology for high resolution physical map construction, but the requirements for assembly ...


An Architecture For Monitoring Visualization And Control Of Gigabit Networks, Guru Parulkar, Douglas Schmidt, Eileen Kraemer, Jonathan Turner, Anshul Kantawala Jan 1997

An Architecture For Monitoring Visualization And Control Of Gigabit Networks, Guru Parulkar, Douglas Schmidt, Eileen Kraemer, Jonathan Turner, Anshul Kantawala

All Computer Science and Engineering Research

We propose a network monitoring, visualization and control system (NMVC) that ensures adequate quality of service to network users while maintaining high network resource utilization. The main components of our system are a network probe, an endsystem probe, software network management agents that provide extensible multi-attribute event filtering for highly scalable data/event collection, network operation centers (NOCs) which can remotely install and (re)configure these agents, efficient online event ordering algorithms that can help synthesize and display a consistent view of network health, status and performance and a View Choreographer that allows management applications and administrators to specify the ...


Eliding The Arguments Of Cases, Ronald P. Loui, Jeff Norman Jan 1997

Eliding The Arguments Of Cases, Ronald P. Loui, Jeff Norman

All Computer Science and Engineering Research

No abstract provided.


Cappucino: An Extensible Planning Tool For Constraint-Based Atm Network Design, Inderjeet Singh, Jonathan S. Turner Jan 1997

Cappucino: An Extensible Planning Tool For Constraint-Based Atm Network Design, Inderjeet Singh, Jonathan S. Turner

All Computer Science and Engineering Research

Cappuccino is a planning tool for topological design of ATM networks. It uses a novel constraint-based approach to ATM network design. Extensibility of the tool is a basic design goal and the tool provides an open interface to incorporate new algorithms.